/Engine/Plugins/FX/Niagara/Source/Niagara/Public/NiagaraParameterStore.h
Adds the passed parameter to this store. Does nothing if this parameter is already present. Returns true if we added a new parameter.
virtual bool AddParameter ( const [FNiagaraVariable](API\Plugins\Niagara\FNiagaraVariable) & Param, bool bInitialize, bool bTriggerRebind, int32 * OutOffset )